Sizing composition for mineral fibers and resulting products

ABSTRACT

The present invention relates to a sizing composition for mineral fibers, especially glass fibers or rock fibers, containing a liquid phenolic resin having a free formaldehyde content, expressed with respect to the total weight of liquid, of 0.1% or less and a compound capable of reacting with the free formaldehyde. 
     Preferably, the liquid phenolic resin is mainly composed of phenol-formaldehyde and phenol-formaldehyde-amine condensates and has a water dilutability, at 20° C., at least equal to 1000%. 
     Another subject of the present invention is the insulating products based on mineral fibers treated by said sizing composition.

The invention relates to a sizing composition for mineral fibers,especially glass fibers or rock fibers, which has a low content of freeformaldehyde. The sizing composition comprises a resin obtained by thecondensation of phenol, formaldehyde and an amine in the presence of abasic catalyst, and a formaldehyde trap.

The invention also relates to the insulating products based on mineralfibers treated by said sizing composition.

The insulating products based on mineral fibers may be formed fromfibers obtained by various processes, for example using the knowntechnique of internal or external centrifugal fiberizing.

Internal centrifugation consists in introducing molten material (ingeneral glass or rock) into a spinner that has a multitude of smallholes, the material being projected against the peripheral wall of thespinner under the action of the centrifugal force and escaping therefromin the form of filaments. On leaving the spinner, the filaments areattenuated and entrained by a high-velocity high-temperature gas streamto a receiving member in order to form a web of fibers.

As for external centrifugation, this consists in pouring the moltenmaterial onto the outer peripheral surface of rotary members known asrotors, from which the molten material is ejected under the action ofthe centrifugal force. Means for attenuating via a gas stream and forcollecting on a receiving member are also provided.

To assemble the fibers together and provide the web with cohesion, thefibers, on leaving the spinner, are sprayed with a sizing compositioncontaining a thermosetting resin. The web of fibers coated with the sizeundergoes a heat treatment (at a temperature generally above 100° C.) soas to polycondense the resin and thus obtain a thermal and/or acousticinsulation product having specific properties, especially dimensionalstability, tensile strength, thickness recovery after compression, anduniform color.

The sizing composition is usually sprayed onto the fibers. Generally,the sizing composition contains the resin, which customarily takes theform of an aqueous solution, additives, such as urea, silanes, mineraloils, aqueous ammonia and a polycondensation catalyst, and water.

The properties of the sizing composition depend largely on thecharacteristics of the resin. From the standpoint of the application, itis necessary for the sizing composition to have good sprayability and beable to be deposited on the surface of the fibers so as to bond themeffectively. The sprayability is directly related to the capability thatthe resin possesses of being able to be diluted in a large amount ofwater and to remain stable over time.

The dilution capability is characterized by the “dilutability”, which isdefined as the volume of deionized water that it is possible, at a giventemperature, to add to a unit volume of the aqueous resin solutionbefore the appearance of permanent cloudiness. In general, a resin isconsidered to be able to be used as a size when its dilutability at 20°C. is 1000% or higher.

The sizing composition is generally prepared at the time of use bymixing the resin and the abovementioned additives. It is important thatthe resin remains stable for a given period of time before being used inthe sizing composition, in particular for at least 8 days at atemperature of around 12 to 18° C. and that its dilutability at the endof this period is, at 20° C., 1000% or higher, preferably 2000% orhigher (infinite dilutability).

Furthermore, the sizing compositions are subject to strict regulationswhich mean that the resin must contain—and generate during the sizingoperation or subsequently during the curing of the insulating product—asfew as possible compounds considered to be harmful to human health or tothe environment.

The thermosetting resins most commonly used in sizing compositions arephenolic resins belonging to the family of resols. Apart from their goodcrosslinkability under the aforementioned thermal conditions, theseresins are very soluble in water, possess good affinity for mineralfibers, especially glass fibers, and are relatively inexpensive.

These resins are obtained by the condensation of phenol andformaldehyde, in the presence of a basic catalyst, in aformaldehyde/phenol molar ratio generally greater than 1 so as topromote the reaction between the phenol and the formaldehyde and toreduce the residual phenol content in the resin.

To reduce the amount of residual formaldehyde, it is known to add asufficient amount of urea to the resin, the urea reacting with the freeformaldehyde, forming urea-formaldehyde condensates (see EP 0 148 050A1). The resin obtained contains phenol-formaldehyde andurea-formaldehyde condensates, has a free formaldehyde and free phenolcontent, expressed with respect to the total weight of liquid, of 3% and0.5%, respectively, or less, and a water dilutability of at least 1000%.

Although the amount of residual phenol is acceptable, the amount ofresidual formaldehyde is however too high to meet the current regulatoryconstraints.

Moreover, it has been found that the resin is not stable under theconditions of the heat treatment to which the sized fibers are subjectedin order for the resin to crosslink and effectively bond the fibers inthe final insulating product. At the temperatures customarily used inthe oven, generally above 100° C., the urea-formaldehyde condensates aredegraded and release formaldehyde, which increases the undesirable gasemissions into the atmosphere. Formaldehyde may also be released fromthe end product during its use as thermal and/or acoustic insulation,under the effect of temperature variations and also hygrometricvariations linked to climatic cycles.

EP 0 480 778 A1 has proposed to substitute part of the urea with anamine, which reacts with the free phenol and the free formaldehyde viathe Mannich reaction to form a condensation product having improvedthermal stability. The free phenol and free formaldehyde contents ofthis resin are 0.20% or less and 3% or less, respectively.

The objective of the present invention is to provide a sizingcomposition capable of being sprayed onto mineral fibers which comprisesa liquid phenolic resin that has a low content of free formaldehyde anda compound capable of reacting with the formaldehyde.

One subject of the invention is, more generally, a resin compositionthat comprises a liquid phenolic resin having a low content of freeformaldehyde and a compound capable of reacting with the formaldehyde.This resin composition is intended, in particular, to be incorporatedinto the constitution of the aforementioned sizing composition.

Another subject of the invention relates to the thermal and/or acousticinsulation products obtained from mineral fibers sized with theaforementioned sizing composition.

The liquid resin that is incorporated into the constitution of thesizing composition according to the invention has a free formaldehydecontent, expressed with respect to the total weight of liquid, of 0.1%or less, preferably of 0.05% or less.

The free phenol content of the resin is, expressed with respect to thetotal weight of liquid, 0.5% or less, preferably 0.4% or less.

Advantageously, the resin is a liquid resin which mainly containsphenol-formaldehyde (P-F) and phenol-formaldehyde-amine (P-F-A)condensates. It is understood here that the “phenol” part, denoted by P,of the condensates may be composed of (i) phenol, or (ii) phenolsubstituted by at least one functional group (such as halo-, nitro-,alkyl-), or (iii) an optionally substituted phenol group borne by along-chain molecule, or (iv) a mixture of the aforementioned compounds(I), (ii), (iii).

The resin has a dilutability, measured at 20° C., at least equal to1000%, preferably 1200% or higher and advantageously 1400% or higher.

The resin is thermally stable since it is free of urea-formaldehyde(U-F) condensates known for their aptitude to degrade under the effectof temperature. As for the P-F-A condensates, these are stable under theaforementioned conditions, notably they generate little formaldehyde, inparticular during aging of the final insulating product.

The resin as defined above is obtained according to a process thatconsists in reacting a phenol as defined previously, preferably phenol,and formaldehyde in the presence of a basic catalyst, in aformaldehyde/phenol molar ratio greater than 1, in cooling the reactionmixture and in introducing into said reaction mixture, during thecooling, an amine that reacts with the free formaldehyde and the freephenol via the Mann ich reaction.

As soon as the amine is introduced the cooling is interrupted and thereaction mixture is maintained at the introduction temperature for atime that varies from 10 to 120 minutes, and after the cooling an acidis added in a sufficient amount so that the pH of the resin is less than7.

Preferably, the phenol and the formaldehyde are made to react in aformaldehyde/phenol molar ratio of between 2 and 4, or advantageouslyless than or equal to 3, to a degree of phenol conversion of greaterthan or equal to 93%, and cooling of the reaction mixture is started.The cooling takes place at a stage in the condensation that correspondsto a resin that can still be diluted with water (dilutability greaterthan 1000%).

The expression “degree of phenol conversion” is understood to mean thepercentage of phenol that has participated in the condensation reactionwith the formaldehyde relative to the starting phenol content.

The amine is added progressively during the cooling since the reactionbetween phenol and formaldehyde is exothermic, and the temperature atthe moment of addition of the amine is maintained over the timementioned above, while taking measures to ensure that the dilutabilityof the resin remains at least equal to 1000%.

The amine is chosen from amines that can react with formaldehyde andphenol to form a Mannich base. As examples, mention may be made ofalkanolamines, in particular monoethanolamine and diethanolamine, andcyclic amines, in particular piperidine, piperazine, and morpholine.Monoethanolamine and diethanolamine are preferred.

The amine is introduced right from the start of the cooling, at atemperature that may vary from 50 to 65° C., preferably of about 60° C.

The phase during which the temperature is maintained allows the amine tobe reacted with almost all of the formaldehyde present in the reactionmedium, and consequently allows the free formaldehyde content in thefinal resin to be lowered down to a value of 0.1% or less.

By maintaining the mixture at the abovementioned temperature, it is alsopossible to reduce the free phenol content in the resin, in particularwhen the latter is obtained with a formaldehyde/phenol molar ratio ofless than 3. The free phenol content in the resin is thus 0.5% or less.

The preparation of the resin takes place under a temperature cycle,which comprises three phases: a heating phase; a first temperature hold;and a cooling phase.

In the first phase, formaldehyde and phenol are made to react in thepresence of a basic catalyst, while progressively heating to atemperature between 60 and 75° C., preferably about 70° C. Theformaldehyde/phenol molar ratio is greater than 1, preferably variesfrom 2 to 4 and is advantageously equal to 3 or less.

The catalyst may be chosen from catalysts known to those skilled in theart, for example triethylamine, lime (CaO) and alkali or alkaline-earthmetal hydroxides, for example sodium hydroxide, potassium hydroxide,calcium hydroxide or barium hydroxide. Sodium hydroxide is preferred.

The amount of catalyst varies from 2 to 15%, preferably 5 to 9% andadvantageously 6 to 8% by weight relative to the initial weight ofphenol.

In the second phase, the temperature of the reaction mixture, which isreached after heating the reaction mixture (end of the first phase), ismaintained until the degree of phenol conversion is at least equal to93%.

The third phase is a cooling phase during which the amine is introducedinto the reaction mixture so as to start the reaction with the residualformaldehyde and the residual phenol, and thus to form the P-F-Acondensates.

The addition of the amine takes place progressively owing to theexothermic character of the reaction, as indicated above, and may forexample be carried out at a rate of from 1 to 5%, preferably 2 to 4%, byweight of the total amount of amine per minute.

The amount of amine, in particular of alkanolamine, is added in anamount of 0.2 to 0.7 mol, preferably 0.25 to 0.5 mol, of amine per moleof starting phenol.

The duration of the amine addition may vary from 10 to 120 minutes,preferably 20 to 100 minutes and advantageously 25 to 50 minutes.

Preferably, the addition of the amine is carried out at a temperaturebetween 50 and 65° C. and advantageously of about 60° C.

After the amine has been added, a temperature hold is effected bymaintaining the temperature at the end of the introduction for 10 to 120minutes, preferably at least 15 minutes, so as to continue thecondensation reaction of the formaldehyde and the phenol with the amineuntil a more advanced stage and further reduce the amount of freeformaldehyde and free phenol, the dilutability of the resin, measured at20° C., having to be maintained at least at 1000%.

After the P-F-A condensates have been formed, the reaction mixture iscooled so that its temperature reaches about 20 to 25° C. and isneutralized so as to stop the condensation reactions.

The reaction mixture is neutralized by adding an acid until a pH of lessthan 7, preferably less than 6 and advantageously above 4 and betterstill of around 5 is obtained. The acid is chosen from sulfuric acid,sulfamic acid, phosphoric acid and boric acid. Sulfuric acid andsulfamic acid are preferred.

The compound capable of reacting with the formaldehyde is chosen from:

1—compounds having active methylene(s), preferably corresponding to thefollowing formulae:

in which:

-   -   R₁ and R₂, which are identical or different, represent a        hydrogen atom, a C₁-C₂₀, preferably C₁-C₆, alkyl radical, an        amino radical or a radical of formula:

-   -   -   in which R₄ represents a

-   -   -   radical where R₅=H or —CH₃ and p is an integer that varies            from 1 to 6;

    -   R₃ represents a hydrogen atom, a C₁-C₁₀ alkyl radical, a phenyl        radical or a halogen atom;

    -   a is equal to 0 or 1;

    -   b is equal to 0 or 1; and

    -   n is equal to 1 or 2.

The preferred compounds of formula (I) are:

-   2,4-pentanedione:-   R₁=—CH₃; R₂=—CH₃; R₃=H; a=0; b=0; n=1;-   2,4-hexanedione:-   R₁=—CH₂—CH₃; R₂=—CH₃; R₃=H; a=0; b=0; n=1;-   3,5-heptanedione:-   R₁=—CH₂—CH₃; R₂=—CH₂—CH₃; R₃=H; a=0; b=0; n=1;-   2,4-octanedione:-   R₁=—CH₃; R₂=—(CH₂)₃—CH₃; R₃=H; a=0; b=0; n=1;-   acetoacetamide:-   R₁=—CH₃; R₂=—NH₂; R₃=H; a=0; b=0; n=1;-   acetoacetic acid:-   R₁=—CH₃; R₂=H; R₃=H; a=0; b=1; n=1;-   methyl acetoacetate:-   R₁=—CH₃; R₂=—CH₃; R₃=H; a=0; b=1; n=1-   ethyl acetoacetate:-   R₁=—CH₃; R₂=—CH₂—CH₃; R₃=H; a=0; b=1; n=1;-   n-propyl acetoacetate:-   R₁=—CH₃; R₂=—(CH₂)₂—CH₃; R₃=H; a=0; b=1; n=1,-   isopropyl acetoacetate:-   R₁=—CH₃; R₂=—CH(CH₃)₂; R₃=H; a=0; b=1; n=1;-   isobutyl acetoacetate:-   R₁=—CH₃; R₂=—CH₂—CH(CH₃)₂; R₃=H; a=0; b=1; n=1;-   t-butyl acetoacetate:-   R₁=—CH₃; R₂=—C(CH₃)₃; R₃=H; a=0; b=1; n=1;-   n-hexyl acetoacetate:-   R₁=—CH₃; R₂=—(CH₂)₅—CH₃; R₃=H; a=0; b=1; n=1;-   malonamide:-   R₁=—NH₂; R₂=—NH₂; R₃=H; a=0; b=0; n=1;-   malonic acid:-   R₁=H; R₂=H; R₃=H; a=1; b=1; n=1;-   dimethyl malonate:-   R₁=—CH₃; R₂=—CH₃; R₃=H; a=1; b=1; n=1;-   diethyl malonate:-   R₁=—CH₂—CH₃; R₂=—CH₂—CH₃; R₃=H; a=1; b=1; n=1;-   di-n-propyl malonate:-   R₁=—(CH₂)₂—CH₃; R₂=—(CH₂)₂—CH₃; R₃=H; a=1; b=1; n=1;-   diisopropyl malonate:-   R₁=—CH(CH₃)₂; R₂=—CH(CH₃)₂; R₃=H; a=1; b=1; n=1;-   di-n-butyl malonate:-   R₁=—(CH₂)₃—CH₃; R₂=—(CH₂)₃—CH₃; R₃=H; a=1; b=1; n=1;-   acetonedicarboxylic acid:-   R₁=H; R₂=H; R₃=H; a=1; b=1; n=2;-   dimethyl acetonedicarboxylate:-   R₁=—CH₃; R₂=—CH₃; R₃=H; a=1; b=1; n=2;-   1,4-butanediol diacetate:-   R₁=—CH₃; R₂=—(CH₂)₄—O—CO—CH₂—CO—CH₃; R₃=H; a=0; b=1; n=1;-   1,6-hexanediol diacetate:-   R₁=—CH₃; R₂=—(CH₂)₆—O—CO—CH₂—CO—CH₃; R₃=H; a=0; b=1; n=1;-   methacryloxyethyl acetoacetate:-   R₁=—CH₃; R₂=—(CH₂)₂—O—CO—C(CH₃)⁼CH₂; R₃=H; a=0; b=1; n=1.)

FORMULA (II)

R₆—CHR₇—C≡N  (II)

in which:

-   -   R₆ represents a cyano radical or a

-   -   in which:        -   R₈ represents a hydrogen atom, a C₁-C₂₀, preferably C₁-C₆,            alkyl radical or an amino radical;        -   c is equal to 0 or 1; and    -   R₇ represents a hydrogen atom, a C₁-C₁₀ alkyl radical, a phenyl        radical or a halogen atom.

The preferred compounds of formula (II) are:

-   2-methyl cyanoacetate:-   R₆=—CO—O—CH₃; R₇=H;-   2-ethyl cyanoacetate:-   R₆=—CO—O—CH₂—CH₃; R₇=H;-   2-n-propyl cyanoacetate:-   R₆=—CO—O—(CH₂)₂—CH₃; R₇=H;-   2-isopropyl cyanoacetate:-   R₆=—CO—O—CH(CH₃)₂; R₇=H;-   2-n-butyl cyanoacetate:-   R₆=—CO—O—(CH₂)₃CH₃; R₇=H;-   2-isobutyl cyanoacetate:-   R₆=—CO—O—CH₂—CH(CH₃)₂; R₇=H;-   2-tert-butyl cyanoacetate:-   R₆=—CO—O—C(CH₃)₃; R₇=H;-   2-cyanoacetamide:-   R₆=—CO—NH₂; R₅=H;-   propanedinitrile:-   R₆=—CEN; R₅=H.

-   -   in which:        -   R₉ represents a —C≡N or —CO—CH₃ radical; and        -   q is an integer that varies from 1 to 4.

The preferred compounds of formula (III) are:

-   trimethylolpropane triacetoacetate:-   R₉=—CO—CH₃; q=1;-   trimethylolpropane tricyanoacetate:-   R₉=—CEN; q=1.

-   -   in which:        -   A represents a —(CH₂)₃— or —C(CH₃)₂— radical; and        -   r is equal to 0 or 1.

The preferred compounds of formula (IV) are:

-   1,3-cyclohexanedione:-   A=—(CH₂)₃; r=0;-   Meldrum's acid:-   A=—C(CH₃)₂—; r=1;    -   2—alcohols, for example monoalcohols such as benzyl alcohol and        polyols such as diethylene glycol, pentaerythritol, inositol and        sorbitol, in particular d-sorbitol;    -   3—phenolic compounds, for example phenol, substituted phenols        such as o-cresol, m-cresol, p-cresol and substituted cresols,        resorcinol and phloroglucinol;    -   4—amines, for example:    -   a) alkanolamines such as diethanolamine and triethanolamine;    -   b) polyamines such as polyethylene amines, especially diethylene        triamine, triethylene tetramine, tetraethylene pentamine and        derivatives thereof, for example in the form of salts, and        amines derived from urea such as guanidine, melamine, ammeline,        benzoguanamine, acetoguanamine, dicyandiamide and thiourea;    -   c) aromatic amines such as para-aminobenzoic acid, aniline and        derivatives thereof, for example in the form of salts;    -   d) amino acids, for example glycine, lysine and threonine;    -   e) polyamidoamines;    -   5—amides, for example urea, 1,3-dimethylurea, ethyleneurea and        derivatives thereof such as N-hydroxyethyleneurea,        N-aminoethylethyleneurea,        N-(3-allyloxy-2-hydroxypropyl)aminoethylethyleneurea,        N-acryloxyethyl-ethyleneurea, N-methacryloxyethylethyleneurea,        N-acrylaminoethylethylene-urea,        N-methacrylaminoethylethyleneurea,        N-methacryloxyacetoxyethylene-urea,        N-methacryloxyacetaminoethylethyleneurea and        N-di(3-allyoxy-2-hydroxypropyl)aminoethylethyleneurea, biurea,        biuret, triuret, acrylamide, methacrylamide, polyacrylamides and        polymethacrylamides;    -   6—hydrazides, for example:    -   a) monohydrazides of formula R₁CONHNH₂ in which R₁ represents an        alkyl radical, for example a methyl, ethyl, n-propyl, isopropyl,        n-butyl, sec-butyl or tert-butyl radical, or an aryl radical,        for example a phenyl, biphenyl or naphthyl radical, it being        understood that a hydrogen atom from said alkyl or aryl radicals        may be replaced by a hydroxy group or a halogen atom, and said        aryl radical may be substituted by an alkyl radical, for example        a methyl, ethyl or n-propyl radical;    -   b) dihydrazides of formula H₂NHN—X—NHNH₂ in which X represents a        —CO— or —CO—Y—CO radical, and Y is an alkylene radical, for        example a methylene, ethylene or trimethylene radical, or an        arylene radical, for example a phenylene, biphenylene or        naphthylene radical, it being understood that a hydrogen atom        from said alkylene or arylene radicals may be replaced by a        hydroxy group or a halogen atom, and said aryl radical may be        substituted by an alkyl radical, for example a methyl, ethyl or        n-propyl radical. As examples, mention may be made of oxalic        acid dihydrazide, malonic acid dihydrazide, succinic acid        dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide,        maleic acid dihydrazide, fumaric acid dihydrazide, diglycolic        acid dihydrazide, tartaric acid dihydrazide, malic aicd        dihydrazide, isophthalic acid dihydrazide terephthalic acid        dihydrazide and carbohydrazide;    -   c) polyhydrazides such as trihydrazides, in particular citric        acid trihydrazide, pyromellitic acid trihydrazide,        1,2,4-benzenetrihydrazide, nitriloacetic acid trihydrazide and        cyclohexanetricarboxylic acid trihydrazide, tetrahydrazides, in        particular ethylenediaminetetraacetic acid tetrahydrazide,        1,4,5,8-naphthoic acid tetrahydrazide, and polyhydrazides formed        from a hydrazide monomer containing a polymerizable group, for        example a poly(acrylic acid hydrazide) or a poly(methacrylic        acid hydrazide);    -   7—aromatic nitrogen-containing heterocyclic compounds, for        example pyrrole, indole, triazoles, especially 1,2,3-triazole        and 1,2,4-triazole, diazines, especially pyrazine, pyrimidine        and pyrazidine, and derivatives thereof, and triazines,        especially 1,2,3-triazine, 1,2,4-triazine and 1,3,5-triazine,        and derivatives thereof;    -   8—sulfites, for example ammonium, potassium or sodium        bisulfites, and metabisulfites of alkali metals, especially        sodium, or of alkaline-earth metals;    -   9—sulfamates, for example sodium or ammonium sulfamate;    -   10—imides, for example succinimide and phthalimide;    -   11—natural products, for example soft wheat flour, wheat flour,        charcoal, animal or plant proteins, such as soybean proteins,        and hydrolyzates of these proteins, tannins especially condensed        tannins, such as tannins from mimosa, quebracho, pine, pecan        nut, hemlock wood and sumac, and polysaccharides that may or may        not be chemically modified, such as hydrolyzed or unhydrolyzed        starches and heteropolysaccharides, especially chitosan;    -   12—sulfur dioxide.

The sizing composition may also comprise 0 to 40 parts of urea per 100parts by dry weight of the mixture constituted by the resin and theurea.

In the sizing composition, the content of the compound capable ofreacting with the formaldehyde represents 1 to 35 parts per 100 parts bydry weight of liquid resin and where appropriate of urea, preferably 1to 30 parts, advantageously is 20 parts or less, for example from 3 to20 parts and in particular is 15 parts or less.

Generally, the sizing composition also comprises the followingadditives, per 100 parts by dry weight of resin and where appropriate ofurea:

-   -   0 to 10 parts of a polycondensation catalyst, for example        ammonium sulfate, preferably less than 7 parts;    -   0 to 2 parts of silane, in particular an aminosilane;    -   0 to 20 parts of oil, preferably 6 to 15 parts; and    -   0 to 20 parts of aqueous ammonia (20 wt % solution), preferably        less than 12 parts.

The role of the additives is known and is briefly recalled: the ureamakes it possible to adjust the gel time of the sizing composition inorder to prevent any pregelling problems; the ammonium sulfate serves asa polycondensation catalyst (in the hot oven) after the sizingcomposition has been sprayed onto the fibers; the silane is a couplingagent for coupling between the fibers and the resin and also acts as ananti-ageing agent; the oils are hydrophobic anti-dust agents; theaqueous ammonia acts, when cold, as a polycondensation retarder.

The sizing composition may be prepared extemporaneously, for animmediate application to the mineral fibers, by mixing the variousconstituents.

The sizing composition may also be prepared by using a resincomposition, which may be known as a “premix”, containing the resin andthe compound capable of reacting with the formaldehyde, optionally urea,to which the other additives are added. The resin composition has abetter stability than the resin alone, which enables the dilutability tobe maintained at a level compatible with the conditions for applicationto the mineral fibers over a longer storage time.

The examples that follow allow the invention to be illustrated withouthowever limiting it.

In the examples, the following analytical methods are used:

-   -   the amount of free phenol is measured by gas chromatography        using a filled column (stationary phase: Carbowax 20 M) and a        flame ionization detector (FID);    -   the amount of free formaldehyde is measured by high-performance        liquid chromatography (HPLC) and post-column reaction under the        conditions of the ASTM D 5910-96 standard modified in that the        mobile phase is water buffered to pH 6.8, the oven temperature        is equal to 90° C. and the detection is carried out at 420 nm;        and    -   the formaldehyde emissions coming from an insulation product        based on glass wool are measured under the conditions of the ISO        16000 and EN 13419 standards. The measurement of the        formaldehyde released is carried out after 3 days of testing at        a temperature of 23° C. and under a relative humidity of 50%.

EXAMPLE 1

Introduced into a 2-liter reactor topped with a condenser and equippedwith a stirring system were 378 g of phenol (4 mol) and 809 g offormaldehyde (10 mol) as a 37% aqueous solution (formaldehyde/phenolmolar ratio equal to 2.5) and the mixture was heated at 45° C. withstirring.

52.7 g of sodium hydroxide as a 50% aqueous solution (i.e. 7% by weightrelative to the phenol) were regularly added over 30 minutes, thetemperature was then progressively raised to 70° C. over 30 minutes, andthis temperature was maintained for 80 minutes so as to reach a degreeof phenol conversion equal to 93%.

Next, the temperature was reduced to 60° C. over 30 minutes and at thesame time 75.3 g of monoethanolamine (1.2 mol) were introduced in aregular manner into the reaction mixture. The temperature was maintainedat 60° C. for 15 minutes, the mixture was cooled down to about 25° C.over 30 minutes, and sulfamic acid as a 15% solution was added over 60minutes until the pH was equal to 5.0.

The resin obtained had the appearance of a clear aqueous composition: ithad a free formaldehyde content equal to 0.05%, a free phenol contentequal to 0.2% (the contents being expressed with respect to the totalweight of liquid) and a dilutability greater than 2000%.

The solids content of the liquid resin, by weight, was adjusted to 50%with water, and urea (20 parts by weight per 80 parts by dry weight ofthe liquid resin) was added. The mixture was kept at 12° C. for 7 days.This mixture was called reference resin composition 1.

Application to the Preparation of a Size

a) Preparation and Use of the Size

A sizing composition was prepared by mixing 100 parts by dry weight ofthe aforementioned mixture of resin and urea, 10 parts by weight ofacetoacetamide, 3 parts of ammonium sulfate, 1 part of silane (Silquest®A-1100 sold by OSI) and 8 parts of a mineral oil.

This sizing composition was used to fabricate an insulating productbased on mineral wool. Conventionally, the sizing composition wassprayed onto glass fibers at the outlet from the fiberizing device in anamount of 4.5% by dry weight of size relative to the weight of thefibers. The sized fibers were collected on a belt conveyor where theyformed a glass wool blanket, which was then subjected to a heattreatment in an oven in order to obtain a minimum temperature of 200° C.in the middle of the product.

The final insulating product had a nominal thickness of 200 mm and anominal density of 11 kg/m³.

a′) Preparation of a Comparative Product

The comparative product was fabricated with a sizing composition thatwas identical in every respect but that did not contain acetoacetamide,all the other parameters for fabrication of the product also being thesame.

b) Measurement of the Formaldehyde Emissions

The formaldehyde emissions generated by the product obtained with thesizing composition according to the invention were three times lowercompared to the formaldehyde emissions released by the comparativeproduct.

c) Measurement of the Stability of the Size

A simplified sizing composition was prepared by mixing the referenceresin composition 1 with acetoacetamide in an amount of 100 parts by dryweight of resin and urea per 10 parts by weight of acetoacetamide.

Table 1 collates the dilutability measurements of the sizing compositionaccording to the invention (with acetoacetamide) and of the referenceresin composition (without acetoacetamide), after a storage period of 3,6, 9 and 12 days at 8° C. and 12° C.

TABLE 1 Sizing composition Reference resin according to the inventioncomposition 8° C. 0 day ≧2000% ≧2000%  3 days ≧2000% 1800% 6 days ≧2000%1600% 9 days ≧2000% 1300% 12 days  1700% 1200% 12° C. 0 day ≧2000%≧2000%  3 days ≧2000% 1600% 6 days  2000% 1200% 9 days  1400%  800% 12days  1100%  600%

EXAMPLES 2 TO 8

A liquid resin was prepared under the conditions from example 1,modified in that the solids content of the resin was adjusted to 43.6%.

20 parts by weight of urea were added to 80 parts by dry weight of theresin in order to obtain a reference resin composition 2, which had adilutability greater than 2000%. The reference resin composition 2 waskept under conditions that simulated aging during storage and led to areduction in the dilutability.

Sizing compositions were then prepared containing 100 parts by dryweight of the mixture of resin and urea and a variable amount (10 or 20parts by weight) of a compound below capable of reacting with theformaldehyde:

-   -   Acetoacetamide: example 2    -   Ethyl acetoacetate: example 3    -   Malonic acid: example 4    -   Dimethyl malonate: example 5    -   Malonamide: example 6    -   Acetonedicarboxylic acid: example 7    -   Dimethyl acetonedicarboxylate: example 8.

Table 2 collates the dilutability measurements of the sizingcompositions and of the resin composition that does not contain acompound capable of reacting with the formaldehyde (Reference 2)measured 24 hours after the preparation of the sizes, all thecompositions (size and reference) having been kept at 23° C.

TABLE 2 Number of parts Dilutability Ex. 2 10 1000% 20 1200% Ex. 3 101000% 20 1200% Ex. 4 10 1900% 20 1800% Ex. 5 10 1000% 20 1200% Ex. 6 101000% 20 1200% Ex. 7 10 1900% 20 1900% Ex. 8 10 1000% 20 1400% Reference—  900%

The addition of a compound capable of reacting with the formaldehydemakes it possible to increase the dilutability of the sizing compositionup to a level that is compatible with the conditions for application tothe mineral fibers (dilutability at least equal to 1000%).

EXAMPLES 9 TO 14

A liquid resin was prepared under the conditions from example 1.

20 parts by weight of urea were added to 80 parts by dry weight of theresin in order to obtain a resin composition.

Two series of sizing compositions were prepared containing 100 parts bydry weight of the resin composition and a variable amount (11.1 parts(series a) or 31.6 parts (series b) by dry weight) of a compound belowcapable of reacting with the formaldehyde:

-   -   Acetoacetamide: example 9    -   Ethyl acetoacetate: example 10    -   Dimethyl acetonedicarboxylate: example 11    -   Adipic acid dihydrazide: example 12    -   Ethyleneurea: example 13    -   Sodium bisulfite: example 14

The sizing compositions from series a and from series b had a solidscontent equal to 35.8% and 27.5% respectively.

For each series, a resin composition was prepared that did not containan agent capable of reacting with the formaldehyde, which had anidentical solids content (References a and b).

The sizing compositions and the resin compositions were stored at 12° C.and their water dilutability was measured at various intervals.

Series a:

Ex. 9 Ex. 10 Ex. 11 Ex. 12 Ex. 14 Ref. a Number of parts 11.1 11.1 11.111.1 11.1 — Dilutability 2 days ≧ 2000% ≧ 2000% ≧ 2000% ≧ 2000% ≧ 2000%≧ 2000% 28 days   800% ≧ 2000%  1000% ≧ 2000%  1400%   500%

Series b:

Ex. 9 Ex. 10 Ex. 11 Ex. 12 Number of parts 31.6 31.6 31.6 31.6Dilutability  8 days ≧2000%  ≧2000% ≧2000%  ≧2000% 34 days 1000% ≧2000%1000% ≧2000% Ex. 13 Ex. 14 Ref. b Number of parts 31.6 31.6 —Dilutability  8 days ≧2000%   ≧2000% ≧2000% 34 days 900% ≧2000%   200%

1. A sizing composition comprising a liquid phenolic resin having a freeformaldehyde content, expressed with respect to the total weight ofliquid, of 0.1% or less and a compound capable of reacting with the freeformaldehyde.
 2. The composition as claimed in claim 1, wherein theliquid phenolic resin consists essentially of phenol-formaldehyde andphenol-formaldehyde-amine condensates.
 3. The composition as claimed inclaim 1, wherein said composition has a free phenol content, expressedwith respect to the total weight of liquid, of 0.5% or less.
 4. Thecomposition as claimed in claim 1, wherein the amine is an alkanolamineor a cyclic amine.
 5. The composition as claimed in claim 4, wherein theamine is monoethanolamine or diethanolamine.
 6. The composition asclaimed in claim 1, wherein the resin has a free formaldehyde content of0.1% or less, a free phenol content of less than 0.4% and a waterdilutability, at 20° C., of 1000% or higher.
 7. The composition asclaimed in claim 1, wherein the compound capable of reacting with theformaldehyde is selected from the group consisting of a compound havingan active methylene, an alcohol, a phenolic compound, an amine, anamide, a hydrazide, an aromatic heterocyclic compound comprisingnitrogen, a sulfite, a sulfamate, an imide, a natural product and sulfurdioxide.
 8. The composition as claimed in claim 7, wherein the compoundhaving an active methylene is represented by one of the formulae (I) to(IV) below:

in which: R₁ and R₂, which are identical or different, represent ahydrogen atom, a C₁-C₂₀, preferably C₁-C₆, alkyl radical, an aminoradical or a radical of formula:

in which R₄ represents a

radical where R₅=H or —CH₃ and p is an integer that varies from 1 to 6;R₃ represents a hydrogen atom, a C₁-C₁₀ alkyl radical, a phenyl radicalor a halogen atom; a is equal to 0 or 1; b is equal to 0 or 1; and n isequal to 1 or 2,R₆—CHR₇—C≡N  (II) in which: R₆ represents a cyano radical or a

in which: R₈ represents a hydrogen atom, a C₁-C₂₀, preferably C₁-C₆,alkyl radical or an amino radical; c is equal to 0 or 1; and R₇represents a hydrogen atom, a C₁-C₁₀ alkyl radical, a phenyl radical ora halogen atom,

in which: R₉ represents a —C≡N or —CO—CH₃ radical; and q is an integerthat varies from 1 to 4,

in which: A represents a —(CH₂)₃— or —C(CH₃)₂— radical; and r is equalto 0 or
 1. 9. The composition as claimed in claim 8, wherein thecompound of formula (I) is selected from the group consisting of2,4-pentanedione, 2,4-hex anedione, 3,5-heptanedione, 2,4-octanedione,acetoacetamide, acetoacetic acid, methyl acetoacetate, ethylacetoacetate, n-propyl acetoacetate, isopropyl acetoacetate, isobutylacetoacetate, t-butyl acetoacetate, n-hexyl acetoacetate, malonamide,malonic acid, dimethyl malonate, diethyl malonate, di-n-propyl malonate,diisopropyl malonate, di-n-butyl malonate, acetonedicarboxylic acid anddimethyl acetonedicarboxylate.
 10. The composition as claimed in claim8, wherein the compound of formula (II) is selected from the groupconsisting of 2-methyl cyanoacetate, 2-ethyl cyanoacetate, 2-n-propylcyanoacetate, 2-isopropyl cyanoacetate, 2-n-butyl cyanoacetate,2-isobutyl cyanoacetate, 2-tert-butyl cyanoacetate, 2-cyanoacetamide andpropanedinitrile.
 11. The composition as claimed in claim 8, wherein thecompound of formula (III) is trimethylolpropane triacetoacetate ortrimethylolpropane tricyanoacetate.
 12. The composition as claimed inclaim 8, wherein the compound of formula (IV) is 1,3-cyclohexanedione orMeldrum's acid.
 13. The composition as claimed in claim 7, wherein thecompound capable of reacting with formaldehyde is at least one amineselected from the group consisting of an alkanolamine, a polyamine, anaromatic amine and a polyamidoamine.
 14. The composition as claimed inclaim 7, wherein the compound capable of reacting with formaldehyde isat least one hydrazide selected from the group consisting of: amonohydrazide of formula R₁CONHNH₂ in which R₁ represents an alkylradical, or an aryl radical, wherein a hydrogen atom from said alkyl oraryl radicals may be replaced by a hydroxy group or a halogen atom, andsaid aryl radical may be substituted by an alkyl radical; a dihydrazideof formula H₂NHN—X—NHNH₂ in which X represents a —CO— or —CO—Y—COradical, and Y is an alkylene radical, or an arylene radical, wherein ahydrogen atom from said alkylene or arylene radicals may be replaced bya hydroxy group or a halogen atom, and said aryl radical may besubstituted by an alkyl radical, for example a methyl, ethyl or n-propylradical; a trihydrazide, a tetrahydrazide and a polyhydrazide formedfrom a hydrazide monomer comprising a polymerizable group, for example apoly(acrylic acid hydrazide) or a poly(methacrylic acid hydrazide). 15.The composition as claimed in claim 1, wherein said composition alsocomprises 0 to 40 parts of urea per 100 parts by dry weight of themixture comprising the resin and the urea.
 16. The composition asclaimed in claim 1, wherein the content of the compound capable ofreacting with the formaldehyde represents 1 to 35 parts per 100 parts bydry weight of liquid resin and optionally urea.
 17. The composition asclaimed in claim 1, wherein said composition also comprises thefollowing additives, per 100 parts by dry weight of liquid resin andwhere appropriate of urea: 0 to 10 parts of a catalyst; 0 to 2 parts ofsilane; 0 to 20 parts of oil; and 0 to 20 parts of aqueous ammonia (20wt % solution).
 18. A resin composition comprising a liquid phenolicresin having a free formaldehyde content, expressed with respect to thetotal weight of liquid, of 0.1% or less and a compound capable ofreacting with the free formaldehyde.
 19. An insulation productcomprising mineral fibers sized with the sizing composition as claimedin claim
 1. 20. A product as claimed in claim 19, wherein the mineralfibers are glass fibers or rock fibers. 21-22. (canceled)
 23. A methodof fabricating an insulation product comprising sizing mineral fiberswith the sizing composition as claimed in claim
 1. 24. A method offabricating an insulation product comprising sizing mineral fibers witha sizing composition comprising the resin of claim 18.